Help with entity procedure

I didn't find any good answer so, I'm making a fallout mod in minecraft and theres this little spider robots that in the original game

are buried in the ground until someone gets close, so in Mcreator I already have an idle buried animation, emerge animation, normal walk animation, attack animation, and normal idle animation

but I can't make a good procedure that: on entity spawn has the buried animation and can't move (slowness level 999) and when detects a player aproach at certain number of blocks

make the emerge animation overriding any other animations, and then start to walk and attach normally, can someone pls help me?